Many clothes are sensitive to moderate or higher mechanical agitation and hot air drying, such that they cannot be washed in a conventional home washer or dried in a convention home dryer. Thus, conventional wisdom generally negates the use of water as a solvent for dry-clean only garments because of the shrinkage associated with conventional washing and drying machines. However, the problem with shrinkage is not the result of the water, but instead is the result of the mechanical action that takes place during normal washing machine cycles and of over heating of the clothing fibers during conventional drying machine cycles. Typical dryers expose garments to air temperatures in excess of 300.degree. F. Typically fabrics start to breakdown at temperatures above 140.degree. F. This fabric breakdown is the lint that is collected in every dryer.
For example, wool may be washed safely in cold water with mild agitation by hand, and then dried by hanging them in ambient air. If wool is exposed to the mechanical agitation of a conventional washer and the drying temperatures of a conventional dryer, it would be irrevocably damaged by mechanical impact and shrinkage. As a result, clothes made of wool or other delicate fibers are dry cleaned by immersion in non-polar hydrocarbon solvents to remove contaminants and are subsequently dried at temperatures that may be lower than the boiling point of water at atmospheric pressure. However, dry cleaning is expensive and hydrocarbon vapors resulting from the drying process may form explosive mixtures with air and are dangerous to personnel and to the environment.
In addition, conventional hot air dryers are inefficient because they do not transfer heat directly from the heat source to the water retained by the clothing. Instead, it is necessary to first heat the air to a relatively high temperature, and then use the hot air to heat the clothing and the walls and internal parts of the dryer, which then transfer the heat to the retained water to vaporize it. In addition, a lot of the heat input is lost in the hot air stream that leaves the drying chamber to transport away the resulting water vapor.